Abstract
Binding to the neonatal Fc receptor (FcRn) extends serum half-life of IgG, and antagonizing this interaction is a promising therapeutic approach in IgG-mediated autoimmune diseases. Fc-MST-HN, designed for enhanced FcRn binding capacity, has not been evaluated in the context of a full-length antibody, and the structural properties of the attached Fab regions might affect the FcRn-mediated intracellular trafficking pathway. Here we present a comprehensive comparative analysis of the IgG salvage pathway between two full-size IgG1 variants, containing wild type and MST-HN Fc fragments, and their Fc-only counterparts. We find no evidence of Fab-regions affecting FcRn binding in cell-free assays, however, cellular assays show impaired binding of full-size IgG to FcRn, which translates into improved intracellular FcRn occupancy and intracellular accumulation of Fc-MST-HN compared to full size IgG1-MST-HN. The crystal structure of Fc-MST-HN in complex with FcRn provides a plausible explanation why the Fab disrupts the interaction only in the context of membrane-associated FcRn. Importantly, we find that Fc-MST-HN outperforms full-size IgG1-MST-HN in reducing IgG levels in cynomolgus monkeys. Collectively, our findings identify the cellular membrane context as a critical factor in FcRn biology and therapeutic targeting.
| Original language | English |
|---|---|
| Article number | 6073 |
| Journal | Nature Communications |
| Volume | 13 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Dec 2022 |
Bibliographical note
Funding Information:The work of M.B. and E.v.d.K. was funded by argenx. E.P., J.A., and S.N.S. were supported by a grant from Flanders Innovation & Entrepreneurship (VLAIO), Belgium. We would like to thank Gerard van Mierlo, Pleuni Ooijevaar-de Heer, and Valerie Hanssens for technical assistance, Ariëlla van den Sompel for statistical analyses, Dr. Vladimir Bobkov for fruitful discussion, and Prof. E. Sally Ward for reading the manuscript. Savvas N. Savvides and Erwin Pannecoucke thank the staff of the EMBL beamlines at synchrotron PETRA3 (Hamburg, Germany) and the staff of Proxima2A at synchrotron SOLEIL (Saclay, France) for synchrotron beam time allocation and technical support.
Publisher Copyright:
© 2022, The Author(s).
Funding
The work of M.B. and E.v.d.K. was funded by argenx. E.P., J.A., and S.N.S. were supported by a grant from Flanders Innovation & Entrepreneurship (VLAIO), Belgium. We would like to thank Gerard van Mierlo, Pleuni Ooijevaar-de Heer, and Valerie Hanssens for technical assistance, Ariëlla van den Sompel for statistical analyses, Dr. Vladimir Bobkov for fruitful discussion, and Prof. E. Sally Ward for reading the manuscript. Savvas N. Savvides and Erwin Pannecoucke thank the staff of the EMBL beamlines at synchrotron PETRA3 (Hamburg, Germany) and the staff of Proxima2A at synchrotron SOLEIL (Saclay, France) for synchrotron beam time allocation and technical support.